Hybrid diesel vehicles include a power take off device powered by batteries. During extended periods of operation, the batteries need to be recharged by the engine. Thus, hybrid diesel vehicles require that the engine be employed in two competing ways. During recharge of the batteries, a hybrid controller controls the engine to run at a preset speed for about 5-minutes to recharge the batteries and to provide power to the power take off device. In contrast, the engine needs to be run about 15-20 minutes to provide sufficient exhaust gas heat to initiate a regeneration event of the diesel particulate filter.
A regeneration event is the periodic oxidation of collected particulate matter that is trapped in a diesel particulate filter during routine diesel engine operation. When the diesel particulate filter of the exhaust system experiences a build-up of particulate matter, the particulate matter is oxidized to “regenerate” the filter. Regeneration is initiated by increasing engine load and activating a post-injection of diesel fuel into the exhaust stream. This post-injection provides sufficient heat to oxidize the trapped particulate matter within the diesel particulate filter.
Hybrid vehicles use an electric power take off device (ePTO device) that is run off of the motor, and powered by batteries. During extended periods of ePTO operation, the batteries may require charging. When the batteries need to be charged, the hybrid controller will turn on the engine to recharge the batteries. Once this charging is completed, the hybrid controller shuts off the engine. A typical battery recharge cycle lasts about 5 minutes.
Regeneration should not be initiated when the engine is being controlled by the hybrid controller to recharge the batteries. While battery recharge requires the engine to be run for about 5-minutes, regeneration of the diesel particulate filter requires the engine to be run for about 15-20 minutes. If the engine were to recharge the batteries during the entire duration of a regeneration event, it would lead to an overcharge of the batteries. On the other hand, if the engine were to stop running once the batteries are charged while a regeneration event is occurring, the diesel particulate filter would not be effectively regenerated and could be irreparably damaged due to thermal shock.